Four-quark scatterings in QCD III

TL;DR

This paper employs the functional renormalisation group to study the infrared dynamics of 2+1 flavour QCD, accurately modeling chiral symmetry breaking and meson formation without phenomenological parameters.

Contribution

It provides a self-consistent, parameter-free analysis of QCD's infrared behavior, completing previous studies and enabling future investigations into QCD phase structure and parton distributions.

Findings

Quantitative agreement with physical observables

Successful modeling of mesonic bound states

Framework applicable to QCD phase transitions

Abstract

We study the full infrared dynamics of 2+1 flavour QCD with the functional renormalisation group approach. We resolve self-consistently the glue dynamics as well as the dynamics of chiral symmetry breaking. The computation hosts no phenomenological parameter or external input. The only ultraviolet input parameters are the physical ones in QCD: the light and strange quark masses. They are adjusted to the physical ratios of the pion and kaon masses, divided by the pion decay constant. The results for other observables of current first-principles computations are in quantitative agreement with the physical ones. This work completes the series of papers, initiated and furthered in [1,2], on dynamical chiral symmetry breaking and the emergence of mesonic bound states within the functional renormalisation group. As a first application we discuss the formation of light mesonic bound states. Amongst other applications such as the phase structure of QCD, the current work paves the way for studying QCD parton distribution functions within the functional renormalisation group approach to first-principles QCD.